The present invention relates to a method of preventing the rust-forming and adherence between friction material and opposite friction member.
Conventionally, the organic friction materials have been used as the friction materials for the brake or clutch of vehicles, which comprise mixtures of organic binder, reinforcement fibers such as asbestos, steel wool, glass fiber, rock wool, etc., friction modifier and the like, and the cast iron has been used in many cases as the opposite friction member.
These friction materials are used under every possible environments. For example, there is such a case as they are left alone for a long period of time at high temperature and high humidity in the rainy season or the like. In this case, there arise such problems as the rust-forming on the friction material and opposite friction member, the adherence between both materials resulting from said rust-forming, etc.
The invention solves these problems.
Also in the past, in the non-asbestos friction materials containing ferrous materials, such one as made to contain boric acid, phosphoric acid or salts thereof was proposed as an anti-rust agent in U.S. Pat. No. 4,363,884 for the prevention of the rust-forming and adherence of opposite friction member.
However, in the invention, the substance incorporated into the friction material as an additive are not the usual borates, such as borax, but a mixture of boric acid and zinc oxide or a reaction product of boric acid with zinc oxide.